如何通过at（）函数访问2D向量的索引？ [英] How to access to the index of a 2D vector by at() function?

问题描述

我将在成员函数中初始化一个2D向量，其中输入参数计划被输入到函数参数内的确定的索引中。
此外，我不会使用[]操作符成员访问由于安全的东西。
如何使用at（）函数访问2D向量的索引，如下？

I am going to initialize a 2D vector in a member function, where the input arguments are planned to be fed into determined indexes within the function argument. Furthermore, I'm not gonna use [] operator to member access due to safety stuffs. How can I use at() function in order to access to the index of a 2D vector, as below?

vector<vector<double>> weight;

void Connection::setWeight(const double& value, const double& i, const double& j)
{
    // The other scheme except: weight[i][j] = value;
}

推荐答案

$ c>在两次。还要注意，如果 i 和 j 是索引，它们实际上不应该是 double 。

You can use at twice. Also note, if i and j are indexes, they really shouldn't be double.

void Connection::setWeight(const double& value, const size_t& i, const size_t& j)
{
    weight.at(i).at(j) = value;
}

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